Conventionally, agricultural square balers comprise a frame that is towed on a pair of wheels over a field for picking up hay, straw or silage grass and feeding such crop material to a baling chamber in which it is compressed to parallelepiped packages under action of a plunger which reciprocates inside the baling chamber. When the packages have reached a predetermined length a tying mechanism is operated to encircle the completed package with a plurality of strands to form a finished bale which will be ejected out of the baler.
As the outlet of the baling chamber is at a substantial height above the field and positioned in a certain angle, there is a risk of the bales being damaged by their fall from the baling chamber, e.g. because the impact breaks some or all of the strands, or because no proper bale drop is ensured, especially with short bales, which end up standing on end when the bale is dropped. Commonly this problem has been solved by providing a guide or a slide at the exit of the baling chamber for reducing the height from which the bale is released onto the field and/or giving a wanted orientation to the bale. In the art, such apparatus usually is referred to as “bale chute” and examples can be found in WO96/29195 and EP-A-0771522.
EP-0974260 discloses an agricultural baler having a bale chute which comprises a rear portion that is movable between an upper, bale sustaining, position and a lower, bale discharging, position.
In EP-0974260, the rear portion is pivotable about an axis located at its leading edge so that, as it pivots, its trailing edge is lowered closer to the ground to allow the formed bale to slide off the chute and to be lowered gently onto the ground. In this manner the rear portion can be lowered during the time interval of the actual discharge operation only. During the remainder of the baler operation, the rear portion is kept at a level sufficiently high for precluding collision with the ground.
It is has been proposed in EP1935232 to weigh each bale as it is being discharged from the bale chute. Weighing each bale can enable the farmer to assess the yield of a field and can enable a contractor to charge by the weight of the baled material rather than the number of bales.
In EP1935232, the bale chute comprises a rear portion that is pivotable about a horizontal axis to allow each bale to be lowered onto the ground without the bale toppling onto its end as it leaves the bale chute and means for weighing each bale while the whole of its weight is supported by the rear portion of the bale chute. Other arrangements for measuring weight have also been proposed and may be used in implementing the present invention though they are not deemed as accurate as the weighing system of EP1935232.
The facility to display the weight of bales on a monitor visible by the baler operator can be used by the operator to achieve a more uniform crop density. As bales are tied when they reach a predetermined length, they should all have the same density if they have same weight.
Hitherto, the weight of the last bale to be weighed has been displayed to the operator alongside the desired weight. As the operator can vary certain operating parameters in order to vary the crop density, it is possible for the operator to increase or decrease the density to correct for the difference between the measured and the desired weight of the bales.
A problem is however experienced if the crop density is modified by the operator in dependence upon the weight of the last bale discharged from the baler. This is because bales are subject to random variation in their weight even if no modification is made to the parameters affecting the crop density.